# Commission Implementing Decision (EU) 2020/2009 of 22 June 2020 establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for surface treatment using organic solvents including preservation of wood and wood products with chemicals (notified under document C(2020) 4050) (Text with EEA relevance), Division BAT 38: In order to prevent or reduce emissions of treatment chemicals from pressure processes (autoclaves), BAT is to use all of the techniques given below.

Extent: E+W+S+N.I.

Technique
Description
(a)
Process controls to prevent operation unless the treatment vessel door is locked and sealed
The treatment vessel door is locked and sealed once the treatment vessel is loaded and before treatment takes place. Process controls are in place that prevent the operation of the treatment vessel unless the door is locked and sealed.
(b)
Process controls to prevent the treatment vessel from opening while it is pressurised and/or filled with preservative solution
Process controls display the pressure and whether liquid is present in the treatment vessel. They prevent the opening of the treatment vessel while it is still pressurised and/or filled.
(c)
Catch-lock for the treatment vessel door
The door of the treatment vessel is equipped with a catch-lock to prevent the release of liquids in the event that the treatment vessel door needs to be opened in an emergency situation (e.g. door seal is broken). The catch-lock permits the door to be partially opened to release the pressure while retaining liquids.
(d)
Use and maintenance of safety relief valves
Treatment vessels are fitted with safety relief valves to protect the vessels from excessive pressure.
Discharges from valves are directed to a tank of sufficient capacity.
Safety relief valves are regularly inspected (e.g. once every 6 months) for signs of corrosion, contamination or incorrect fitting and are cleaned and/or repaired as required.
(e)
Control of emissions to air from the vacuum pump exhaust
Air extracted from pressure treatment vessels (i.e. the vacuum pump outlet) is treated (e.g. in a vapour-liquid separator).
(f)
Reduction of emissions to air when opening the treatment vessel
Sufficient time for dripping and condensation is allowed between the depressurisation period and the opening of the treatment vessel.
(g)
Application of a final vacuum to remove excess treatment chemicals from the surface of treated wood
To avoid dripping, a final vacuum is applied in the treatment vessel before opening it to remove excess treatment chemicals from the surface of treated wood.
Application of a final vacuum may not be necessary if the removal of excess treatment chemicals from the surface of treated wood is ensured by the application of an appropriate initial vacuum (e.g. less than 50 mbar).

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Source: https://www.legislation.gov.uk/eudn/2020/2009/annex/division/2/division/2.6/division/BATn3 (the official version)
Page: https://openlegislation.uk/eu-decision-2020-2009/annex/division-2/division-2.6/division-BATn3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.